蕉木(Oncodostigma hainanense)内轮花瓣近轴面瘤状突起发育及功能

为正确认识蕉木(Oncodostigma hainanense)内轮花瓣近轴面突起的发育和作用,采用扫描电子显微镜(SEM)观察蕉木内轮花瓣近轴面瘤状突起的形成过程,并采用光学显微镜(LM)观察经PAS染色反应的蕉木内轮花瓣半薄切片的结构。SEM观察发现,蕉木花蕾在发育Ⅰ期和Ⅱ期其内轮花瓣近轴面无明显瘤状突起形成,Ⅲ期有明显的瘤状突起形成,Ⅳ期瘤状突起发育成熟并布满整个内轮花瓣近轴面;LM观察发现,多糖类物质随蕉木内轮花瓣近轴面瘤状突起的发育而增多,并向瘤状突起周边细胞集中;体视显微镜下观察到有蓟马的幼虫在开放的花瓣瘤状突起间活动,但并没有发现瘤状突起表面有泌蜜孔及多糖类物质。推测蕉木内轮花瓣近轴面瘤状突起为访花者提供了繁殖、产卵和孵卵的场所并为它们提供了一定的食物来源(多糖物质)。

Development and Function of the Strumae on the Adaxial Sides of the Inner Petals of Oncodostigma hainanense

Scanning electron microscope (SEM) and light microscope (LM) were used to examine the development and function of the strumae on the adaxial sides of the inner petals of Oncodostigma hainanense. We found that no struma formed at stageⅠ and Ⅱ of bud development. However, obvious strumae were formed at stage Ⅲ, which protruded outwards from the plane of tissue. Strumae were fully developed at stage Ⅳ. The periodic acid-schiff (PAC) reaction indicated that polysaccharides increased with the formation of strumae and were mainly distributed in cells around the strumae at stage Ⅳ. We have observed some thrip larvae among mature strumae, but no secretive opening or secretion on the surface of the strumae was found. We speculated that the strumae on the adaxial sides of the inner petals provided flower visitors a nutritious and safe place for mating, oviposition, brooding and perhaps some food such as polysaccharides.